C# 对话：如何在另一个根元素中创建RadioElement？

我有两个

RootElement

元素。参见代码。最深层应该有tappable

StringElement

，允许选择当前审核。但是，由于缺少

RadioGroup

，我得到了空引用错误。 有没有可能使用MT.Dialog

Root = new RootElement ("Annotations")
{
  new Section ("Review")
  {
    // This element's caption is supposed to be whatever gets selected deep down.
    new RootElement("Reviews", new RadioGroup(0))
    {
      new Section("My Reviews")
      {
        new RootElement("Local profile")
       {
         new Section()
         {
           // Tapping this element should make "Local profile selected" appear as caption of the "Reviews" RootElement.
           new RadioElement("Activate", "Local profile selected")
         },
...more elements...

---

指定无线组，如下所示：

new RootElement ("Local Profile", new RadioGroup (0)) {
    ....
}